Child Support Arrears: How Interest Works

When a support payment is missed, the unpaid amount becomes an arrearage. In many states each missed payment is automatically a final judgment the day it comes due, which means it generally cannot be erased later, only paid. Whether that balance then grows with interest depends entirely on state law.

The National Conference of State Legislatures last surveyed all 51 jurisdictions in October 2021 and found 34 states plus Guam and Puerto Rico authorize interest on child support arrears. That survey is the standard reference, but it is several years old, and market-indexed rates move, so this page leans on the current statutes for the 51 states we cover and flags the survey’s date whenever it is the source.

Most states that charge interest charge simple interest: the rate applies to unpaid principal only, and interest never earns interest. Texas is a fixed 6 percent per year. California is 10 percent, accruing on each installment as it falls due. Illinois charges 9 percent, computed monthly on the unpaid balance. North Carolina’s legal rate is 8 percent.

Compounding is rare. Per the 2021 NCSL survey, Colorado authorizes monthly compounding and Kentucky compounds annually on judgments. Several statutes go out of their way to forbid it: Michigan’s surcharge law says the surcharge shall not compound, and West Virginia bars compounding outright.

A meaningful group of states charges nothing automatically. Pennsylvania support arrears do not accrue interest under the support rules; interest enters only if arrears are reduced to a money judgment at the legal rate. Connecticut, Delaware, Kansas, and about a dozen others authorize no arrears interest at all per the NCSL survey.

Some rates float. Florida’s judgment rate is reset quarterly by its Chief Financial Officer, 8.06 percent per year effective July 1, 2026, though support judgments keep the rate in effect when established. Michigan’s surcharge tracks 5-year Treasury note yields plus 1 percent.

Two states with the same rate can produce very different balances because of when interest starts. In Texas and California, interest accrues on each payment as it becomes delinquent, no court trip required. In New York, arrears earn the 9 percent judgment rate once they are reduced to a money judgment, and interest from the original due dates requires a finding that the default was willful.

Ohio and Michigan gate interest behind judicial discretion. An Ohio court may assess interest on an arrearage only if it finds the failure to pay was willful, at the annually certified judgment rate. A Michigan court may order the surcharge only after finding a willful failure to pay. In both, an arrearage can grow for years with no interest because nobody asked a judge for it.

Georgia splits the difference: 7 percent per year starts 30 days after an installment comes due, but the court has discretion to waive or reduce it for hardship.

State child support agencies do not always compute the interest the statute allows. Illinois policy is explicit that the agency does not routinely calculate interest administratively; a parent seeking it goes through court. So an official agency balance can be lower than a statutory computation, and both can be right for their purpose.

Payment application order matters too. Whether a payment retires current support, principal arrears, or accrued interest first changes every later interest calculation. Our arrears calculators state the rate, the accrual rule, and the assumptions they apply for each state, and the court or agency figure always controls over any estimate.